Research Objective 2. Racial and ethnic differences. Principal Investigator: established investigator Physical functional capacity, defined as the ability to perform physical tasks, declines with age. Eventually this can result in disability, increased use of health care services (and the related costs), loss of independence, and reduced quality of life. Two important physiological determinants of physical functional capacity are maximal aerobic exercise capacity and muscle strength. These two determinants decline with age and thus, contribute to the age-associated reductions in functional capacity. Hispanics are the fastest growing segment of the population, and soon will be the largest minority in the U.S. Recent findings indicate that Hispanic adults, particularly Hispanic women, demonstrate greater age-related declines in physical function than Caucasians (non-Hispanic whites). However, the responsible physiological mechanisms are unknown. Accordingly, the experimental aim of the present proposal is to determine if the declines in maximal aerobic exercise capacity and muscle strength across age are greater in Hispanic compared with Caucasian healthy women. We hypothesize that this will be the case. To test this hypothesis, 60 Hispanic and 60 Caucasian healthy sedentary women aged 20-80 years will be studied from the greater Front Range area of Colorado. Maximal oxygen consumption, knee-extension strength (1 repetition maximum), whole-body and thigh composition, instrumental activities of daily living, dietary composition and intake, habitual physical activity levels, and socio-economic status will be measured. Age-related declines in maximal oxygen consumption and knee-extensor strength will be expressed: a) as absolute levels; and b) normalized for whole-body mass and for fat-free mass maximal oxygen consumption, and for thigh fat-free mass (knee-extensor strength) to account for the potential influence of differences in body composition across age. The results of this study will provide important new insight into the question of whether greater age-related declines in maximal aerobic exercise capacity and/or muscle strength could contribute to the higher prevalence of functional disability reported with age in Hispanic women. Our results also will serve as critical baseline data from which: a) more definitive longitudinal studies of age-related changes in maximal aerobic exercise capacity and muscle strength; and b) exercise intervention studies, can be performed in the future.